Pinpoint Test O: Electronic Shift-On-The-Fly (ESOF) Functional Test
Four Wheel Drive (4WD) Systems - Electronic Shift
Pinpoint Tests
Pinpoint Test O: Electronic Shift-On-The-Fly (ESOF) Functional Test
Refer to Wiring Diagram Set 34, Four-Wheel Drive Systems for schematic and connector information. Diagrams By Number
Normal Operation
When operating in 4H (4X4 HIGH) or 4L (4X4 LOW) mode, the transfer case and the Constant Vacuum Hublock (CVH) at each front wheel are locked. When in 4L mode, the transfer case low range gear set provides an additional 2.72 gear reduction. When operating in 2H (4X2) mode, the transfer case and both CVH are unlocked.
This pinpoint test is intended to diagnose the following:
- No communication with the Instrument Panel Cluster (IPC)
- Transfer case and related components
- CVH system and related components
- Wheel/tire assemblies
PINPOINT TEST O: ESOF FUNCTIONAL TEST
WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
NOTE: 4H (4X4 HIGH) or 4L (4X4 LOW) is not intended for driving on hard/dry surfaces.
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O1 CHECK FOR IPC DTCs
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Self-Test - IPC.
- Are any DTCs present?
Yes
If DTC U0102:00 is retrieved, REFER to Module Communications Network Testing and Inspection to diagnose lost communication with Transfer Case Control Module (TCCM). For all other DTCs, REFER to Instrumentation, Message Center, and Warning Chimes Testing and Inspection.
No
GO to O2.
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O2 CHECK 2H OPERATION
- Stop the vehicle.
- Make sure both CVH dials are in AUTO mode.
- Transmission in NEUTRAL.
- Switch the Mode Select Switch (MSS) to 4H then to 2H.
- Does the IPC 4X4 HIGH indicator turn off and does the message center (if equipped) display 4X2 for approximately 4 seconds?
Yes
GO to O4.
No
GO to O3.
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O3 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM.
- Are DTCs retrieved?
Yes
REFER to the TCCM DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to O4.
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O4 CHECK FOR WIND UP IN TURNS IN 2H
- Make sure both CVH dials are in AUTO mode.
- Drive the vehicle on a dry, hard surface while executing turns.
- Is wind up present in turns?
Yes
GO to Pinpoint Test I. Pinpoint Test I: The Vehicle Does Not Shift Between 2H and 4H Modes Correctly
No
GO to O5.
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O5 CHECK 4H OPERATION
- Stop the vehicle.
- Lock the LH and RH CVHs.
- Transmission in NEUTRAL.
- Switch the MSS to 4H.
- Does the IPC 4X4 HIGH indicator illuminate correctly or message center (if equipped) display 4X4 HIGH?
Yes
GO to O9.
No
GO to O6.
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O6 CHECK FOR RETURN OF TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM.
- Are DTCs retrieved?
Yes
REFER to the TCCM DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to O7.
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O7 CHECK FOR WIND UP IN TURNS IN 4H
- Drive the vehicle in 4H while executing turns.
- Is wind up and tire scuff present?
Yes
GO to O8.
No
GO to Pinpoint Test I. Pinpoint Test I: The Vehicle Does Not Shift Between 2H and 4H Modes Correctly
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O8 CHECK FOR STRAIGHTLINE WIND UP IN 4H
- Drive the vehicle on a dry, hard surface while driving in a straight line.
- Is wind up present?
Yes
GO to Pinpoint Test N. Pinpoint Test N: Vehicle Pulsates or Shudders in a Straight Line (Straight Line Driveline Wind Up)
No
GO to O9.
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O9 CHECK FOR LH AND RH CVH ENGAGEMENT IN 4H
- Switch the MSS to 4H.
- Make sure both CVH dials are in AUTO mode position.
- NOTE: The engine must be at idle during the following steps to supply vacuum for CVH engagement.
- With the vehicle in NEUTRAL, position it on a hoist. Refer to Jacking and Lifting Service and Repair.
- Start the engine and allow to idle.
- Rotate the LH front tire one revolution forward and one revolution backward while observing the LH front axle shaft and U-joint.
- Rotate the RH front tire one revolution forward and one revolution backward while observing the RH front axle shaft and U-joint.
- Does the LH or RH front axle shaft rotate?
Yes
GO to O11.
No
GO to O10.
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O10 CHECK FOR CVH VACUUM LEAKS
- Ignition OFF.
- Disconnect both vacuum tubes from the hublock vacuum solenoid.
- Using a vacuum pump, apply 508 mm (20 in) Hg of vacuum to the CVH vacuum circuit.
- Observe the vacuum reading.
- Did the vacuum drop more than 25 mm (0.984 in) Hg per minute?
Yes
CHECK the CVH and related components for leaks. GO to Pinpoint Test K. Pinpoint Test K: The Front Axles Do Not Engage/Disengage Correctly
No
CONNECT the hublock vacuum solenoid vacuum lines and GO to O11.
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O11 CHECK 4L OPERATION
- Bring the vehicle to a speed below 5 km/h (3 mph). With the transmission in NEUTRAL, switch the MSS to 4L.
- Does the IPC 4X4 LOW indicator illuminate correctly or message center (if equipped) display 4X4 LOW?
Yes
GO to O13.
No
GO to O12.
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O12 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM.
- Are DTCs retrieved?
Yes
REFER to the TCCM DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to O13.
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O13 CHECK FOR WIND UP IN TURNS IN 4L
- Drive the vehicle on a dry, hard surface while turning.
- Is wind up and tire scuff present and 4L operating?
Yes
GO to O14.
No
CHECK for TCCM DTCs. REFER to Inspection and Verification. If no DTCs are present, GO to Pinpoint Test J. Inspection and Verification Pinpoint Test J: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly
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O14 CHECK FOR STRAIGHTLINE WIND UP IN 4L
- Drive the vehicle in 4L while driving in a straight line.
- Is wind up present?
Yes
GO to Pinpoint Test N. Pinpoint Test N: Vehicle Pulsates or Shudders in a Straight Line (Straight Line Driveline Wind Up)
No
GO to O15.
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O15 CHECK 4L TO 2H SHIFT
- With the vehicle at a stop and transmission in NEUTRAL, switch the MSS from 4L to 2H.
- Does the 4X4 LOW indicator turn off or (if equipped)IPC message center display 4X2 for approximately 4 seconds then turn off?
Yes
GO to O17.
No
GO to O16.
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O16 CHECK FOR TCCM DTCs
- Transmission in PARK.
- Enter the following diagnostic mode on the scan tool: Self-Test - TCCM.
- Are DTCs retrieved?
Yes
REFER to the TCCM DTC Chart. Inspection and Verification
No
GO to O17.
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O17 CHECK FOR WIND UP IN TURNS IN 2H
- Drive the vehicle on a dry, hard surface while executing turns.
- Is wind up and tire scuff present in turns?
Yes
GO to Pinpoint Test J. Pinpoint Test J: The Vehicle Does Not Shift Between 4H and 4L Modes Correctly
No
GO to O18.
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O18 CHECK 2H TO 4H SHIFT
- Switch the MSS to 2H.
- Drive the vehicle on the road and shift from 2H to 4H while driving above 32 km/h (20 mph).
- Does the transfer case shift to 4H satisfactorily?
Yes
The 4WD system is operating correctly.
No
GO to Pinpoint Test L. Pinpoint Test L: Four-Wheel Drive (4WD) Does Not Engage at Speed Correctly
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